1. Field of the Invention
The present invention relates to a photosensitive composition useful for forming a color filter to be used a liquid crystal display device and a solid-state imaging device, a dye-containing color filter, and its production method.
2. Description of the Related Art
As a method of producing a color filter to be used for a liquid crystal display device (LCD) and a solid-state imaging device (CCD, CMOS) have been known a dyeing method, a printing method, an electrodeposition method and a pigment dispersion method.
The pigment dispersion method among them is a method of producing a color filter by photolithography using a colored radiation sensitive composition obtained by dispersing various kinds of pigments in a photosensitive composition and since pigments are used, it is advantageous in the stability to light and heat. Also, since patterning is carried out by the photolithographic method, the method has a high positioning precision and been therefore used widely and preferably for producing a color filter for a large screen and highly fine color display.
In the case of producing a color filter by the pigment dispersion method, a radiation-sensitive composition is applied to a glass substrate by a spin coater or a roll coater and dried to form a film and then the film is pattern-wise exposed and developed to form colored pixels and these steps are repeated for respective colors corresponding to a desired number of hues to obtain a color filter. As such a pigment dispersion method is reported an example using a negative type photosensitive composition containing an alkali-soluble resin in combination with a photo-polymerizable monomer and a photopolymerization initiator (e.g. reference to Japanese Patent Laid-Open (JP-A) No. 2-199403).
On the other hand, in these years, it has been desired to make a color filter for a solid-state imaging device finer. However, in a conventional pigment dispersion system, since ultraviolet rays are scattered at the time of exposure, it is difficult to further improve the resolution and a problem of occurrence of color unevenness attributed to coarse particles of a pigment takes place and accordingly it is not suitable for applications for which fine patterns are required just like the solid-state imaging device.
In consideration of the above-mentioned problems, techniques of using dyes in place of pigments have been proposed before (e.g., reference to JP-A No. 6-75375).
Further, in these years, in the case of producing a color filter for a solid-state imaging device, it has also been required to make the filter thinner. To simultaneously satisfy both requirements of sufficient coloring density and thinness, a large quantity of a coloring agent has to be added to a photosensitive composition and contents of other materials have to be decreased. Even if a composition satisfying that is produced, no significant problem is caused in the case of using a pigment for the coloring agent (e.g. reference to JP-A No. 2003-149801).